Design and Control of Mode Interaction in Coupled ZnTe Optical Microcavities

The photonics involving II–VI epitaxial layers was limited so far to structures based on a single planar microcavity. Here, we present double vertically coupled ZnTe optical microcavities in planar and 3-D photonic molecule geometry. We design the structures with the help of transfer matrix method calculations and we establish their fabrication technology using molecular beam epitaxy. We characterize the samples by reflectivity spatial mapping and study them by angle-integrated and angle-resolved photoluminescence and reflectivity. We efficiently tailor the interaction strength of the optical cavities modes by adjusting the spatial separation between the microcavities, their thickness ratio, and the size of the micropillars etched out of the planar structure. Coupling constants extracted from our measurements agree with those determined in calculations in the frame of a tight-binding approach applied to one-dimensional photonic structures

Spin Splitting Anisotropy in Single Diluted Magnetic Nanowire Heterostructures

We study the impact of the nanowire shape anisotropy on the spin splitting of excitonic photoluminescence. The experiments are performed on individual ZnMnTe/ZnMgTe core/shell nanowires as well as on ZnTe/ZnMgTe core/shell nanowires containing optically active magnetic CdMnTe insertions. When the magnetic field is oriented parallel to the nanowire axis, the spin splitting is several times larger than for the perpendicular field. We interpret this pronounced anisotropy as an effect of mixing of valence band states arising from the strain present in the core/shell geometry. This interpretation is further supported by theoretical calculations which allow to reproduce experimental results